Laser has been widely applied in optical fiber communication systems, due to its high directivity, high coherence, high monochrome and other significant advantages. At present, laser is typically generated by a laser device at a constant wavelength, which can only generate laser at the constant wavelength, but there is an increasing demand for laser at different wavelengths in the optical fiber communication systems, due to the development of Dense Wavelength Division Multiplexing (DWDM) technology, so that a large number of laser devices at the different constant wavelengths have to be provided, thus resulting in a growing number of laser devices and an increase in cost thereof.